We are carrying-out peptide analysis and sequencing of two enzymes and a larval protein from Drosphila pseudoobscura. Once the sequence has been determined, we will look for substitutions in large numbers of isogenic lines derived from natural populations and determine how much amino acid variation exists that cannot be detected by gel electrophoresis under various conditions. A second aspect of the experimental work is the survey of several proteins in a very large number of isogenic lines derived from two populations. The survey will use the multi-pass method of gel electrophoresis at different pH's and different gel concentrations to determine how many alleles there are and what their frequency is in each population with some accuracy.